[release-branch.go1.23] all: merge master (8f1ec59) into release-branch.go1.23

Merge List:

+ 2024-07-15 8f1ec59bdb strings: re-introduce noescape wrapper
+ 2024-07-15 5d36bc18d5 net/http: document io.Seeker requirement for fs.FS arguments
+ 2024-07-12 071b8d51c1 cmd: vendor golang.org/x/telemetry@268b4a8ec2d7
+ 2024-07-12 4e77872d16 go/types: fix assertion failure when range over int is not permitted
+ 2024-07-12 8bc32ab6b1 os: clean up after TestIssue60181
+ 2024-07-11 b31e9a63a4 unsafe: say "functions like syscall.Syscall", not only Syscall
+ 2024-07-11 a71bb570d0 all: make struct comments match struct names
+ 2024-07-11 611f18c4e9 strings: more cross-references in docstrings
+ 2024-07-11 08a6e080ca database/sql/driver: fix name in comment
+ 2024-07-11 dfaaa91f05 os: clarify that IsNotExist, IsExist, IsPermission and IsTimeout work with nil errors
+ 2024-07-10 5881d857c5 crypto/tls: add support for -expect-no-hrr to bogo_shim_test
+ 2024-07-10 b3040679ad math: remove riscv64 assembly implementations of rounding
+ 2024-07-10 70e453b436 context: handle nil values for valueCtx.String()
+ 2024-07-09 183a40db6d runtime: avoid multiple records with identical stacks from MutexProfile
+ 2024-07-09 e89e880eac crypto/tls: add support for -reject-alpn and -decline-alpn flags to bogo_shim_test
+ 2024-07-09 73186ba002 crypto/internal/cryptotest: add common tests for the hash.Hash interface
+ 2024-07-08 87ec2c959c testing: remove call to os.Exit in documentation for TestMain
+ 2024-07-08 6d89b38ed8 unsafe: clarify when String bytes can be modified
+ 2024-07-07 5565462a86 cmd/dist: remove iter,slices,maps test on GOEXPERIMENT=rangefunc
+ 2024-07-07 b43d6c57de io: add test for Pipe constructor allocations
+ 2024-07-07 d0146bd85b os/exec: only use cachedLookExtensions if Cmd.Path is unmodified
+ 2024-07-05 ad77cefeb2 cmd/compile: correct RewriteMultiValueCall fatal message
+ 2024-07-05 be152920b9 cmd/compile: fix ICE when compiling global a, b = f()
+ 2024-07-03 82c14346d8 cmd/link: don't disable memory profiling when pprof.WriteHeapProfile is used
+ 2024-07-03 7d19d508a9 cmd/cgo: read CGO_LDFLAGS environment variable
+ 2024-07-03 5f50b1e3bf cmd/compile: fix mis-compilation when switching over channels
+ 2024-07-03 71f9dbb1e4 cmd/compile: emit error message on mismatch import path
+ 2024-07-03 148755a27b cmd/link: document -checklinkname option
+ 2024-07-02 f12ac5be70 time: fix time zone parsing when format includes time zone seconds
+ 2024-07-02 09aeb6e33a os: add TODO about removing test exception
+ 2024-07-01 94982a0782 cmd/go/internal/workcmd: remove a potentially confusing statement
+ 2024-07-01 f71c00b616 cmd/link: align .reloc block starts by 32 bits for PE target
+ 2024-07-01 d3c93f2f00 cmd/go: update go clean help message
+ 2024-07-01 cdbf5f2f7e sync: refer to Locker interface methods in RWMutex.RLocker doc
+ 2024-07-01 c33144c47c runtime: fix nil pointer in TestGoroutineParallelism2 when offline
+ 2024-06-28 82c371a307 cmd/compile: drop internal range-over-func vars from DWARF output
+ 2024-06-28 773767def0 net/http: avoid appending an existing trailing slash to path again
+ 2024-06-28 7f90b960a9 cmd/compile: don't elide zero extension on top of signed values
+ 2024-06-27 ea537cca31 cmd/go/internal/help: add documentation for language version downgrading
+ 2024-06-27 b0927fdd49 slices: update docs for All, Backward, Values
+ 2024-06-26 5a18e79687 cmd/link: don't skip code sign even if dsymutil didn't generate a file
+ 2024-06-26 5f319b7507 cmd/link: don't let dsymutil delete our temp directory
+ 2024-06-26 a2e90be996 os: rewrite TestChtimesWithZeroTimes
+ 2024-06-25 90bcc552c0 crypto/tls: apply QUIC session event flag to QUICResumeSession events
+ 2024-06-25 b1fd047508 cmd/internal/obj/arm64: fix return with register
+ 2024-06-25 b3b4556c24 cmd/compile: update README to reflect dead code elimination changes
+ 2024-06-24 68315bc8ce cmd: run go mod tidy after CL 593684
+ 2024-06-24 f214a76075 cmd/vendor: vendor x/telemetry@38a4430
+ 2024-06-24 29b1a6765f net/http: document that Request.Clone does not deep copy Body
+ 2024-06-24 cf54a3d114 crypto/tls: replay test recordings without network
+ 2024-06-24 b98803e8e5 os: TestChtimes: separate hasNoatime
+ 2024-06-24 0def9d5c02 cmd/internal/obj/arm64: Enable arm64 assembler tests for cross-compiler builds
+ 2024-06-24 085cf0fcdc net/netip: add test that Compare and reflect.DeepEqual match
+ 2024-06-24 740043f516 net/netip: unexport fields of addrDetail
+ 2024-06-23 e8ee1dc4f9 cmd/link/internal/ld: handle "\r" in MinGW "--print-prog-name" output
+ 2024-06-22 44f1870666 cmd/link: handle dynamic import variables on Darwin in plugin mode
+ 2024-06-21 0af2148fdc cmd: vendor golang.org/x/telemetry@a740542
+ 2024-06-21 cb3b34349b doc/next: delete
+ 2024-06-21 d79c350916 cmd/internal: separate counter package from telemetry package
+ 2024-06-21 52ce25b44e cmd/vendor: pull in golang.org/x/telemetry@b4de734
+ 2024-06-21 fed2c11d67 iter: minor doc comment updates
+ 2024-06-21 d73a8a206a cmd/cgo: fail on v, err := C.fn when fn is a builtin function
+ 2024-06-21 1b4f1dc95d os: improve newFile, rm newDir
+ 2024-06-21 72e2220b50 encoding/json: clarify the map's key type for Unmarshal
+ 2024-06-21 e9a306e004 types2, go/types: correct NewTypeParam documentation
+ 2024-06-21 6fea409424 text/template/parse: fix handling of assignment/declaration in PipeNode.String
+ 2024-06-21 d67839f58a crypto/tls: add support for -expect-version to bogo_shim_test
+ 2024-06-21 201129414f sync/atomic: correct result names for Or methods
+ 2024-06-21 20b79fd577 time: provide non-default metric for asynctimerchan
+ 2024-06-20 9d33956503 internal/godebugs: fix old value for httpservecontentkeepheaders
+ 2024-06-20 477ad7dd51 cmd/compile: support generic alias type
+ 2024-06-18 4f77a83589 internal/syscall/unix: fix UTIME_OMIT for dragonfly

Change-Id: I3864b03b8c377e8fe82014eee96dc7b77aea64e2

1 files changed, 35 insertions, 30 deletions

diff --git a/src/os/exec/exec.go b/src/os/exec/exec.go
index 50ed3a8d16..da9f68fe28 100644
--- a/src/os/exec/exec.go
+++ b/src/os/exec/exec.go
@@ -334,8 +334,10 @@ type Cmd struct {
 	lookPathErr error
 
 	// cachedLookExtensions caches the result of calling lookExtensions.
+	// It is set when Command is called with an absolute path, letting it do
+	// the work of resolving the extension, so Start doesn't need to do it again.
 	// This is only used on Windows.
-	cachedLookExtensions string
+	cachedLookExtensions struct{ in, out string }
 }
 
 // A ctxResult reports the result of watching the Context associated with a
@@ -436,12 +438,12 @@ func Command(name string, arg ...string) *Cmd {
 		// Since the path is absolute, its extension should be unambiguous
 		// and independent of cmd.Dir, and we can go ahead and cache the lookup now.
 		//
-		// Note that we cannot add an extension here for relative paths, because
-		// cmd.Dir may be set after we return from this function and that may cause
-		// the command to resolve to a different extension.
-		lp, err := lookExtensions(name, "")
-		cmd.cachedLookExtensions = lp
-		if err != nil {
+		// Note that we don't cache anything here for relative paths, because
+		// cmd.Dir may be set after we return from this function and that may
+		// cause the command to resolve to a different extension.
+		if lp, err := lookExtensions(name, ""); err == nil {
+			cmd.cachedLookExtensions.in, cmd.cachedLookExtensions.out = name, lp
+		} else {
 			cmd.Err = err
 		}
 	}
@@ -642,29 +644,32 @@ func (c *Cmd) Start() error {
 		return c.Err
 	}
 	lp := c.Path
-	if c.cachedLookExtensions != "" {
-		lp = c.cachedLookExtensions
-	}
-	if runtime.GOOS == "windows" && c.cachedLookExtensions == "" {
-		// If c.Path is relative, we had to wait until now
-		// to resolve it in case c.Dir was changed.
-		// (If it is absolute, we already resolved its extension in Command
-		// and shouldn't need to do so again.)
-		//
-		// Unfortunately, we cannot write the result back to c.Path because programs
-		// may assume that they can call Start concurrently with reading the path.
-		// (It is safe and non-racy to do so on Unix platforms, and users might not
-		// test with the race detector on all platforms;
-		// see https://go.dev/issue/62596.)
-		//
-		// So we will pass the fully resolved path to os.StartProcess, but leave
-		// c.Path as is: missing a bit of logging information seems less harmful
-		// than triggering a surprising data race, and if the user really cares
-		// about that bit of logging they can always use LookPath to resolve it.
-		var err error
-		lp, err = lookExtensions(c.Path, c.Dir)
-		if err != nil {
-			return err
+	if runtime.GOOS == "windows" {
+		if c.Path == c.cachedLookExtensions.in {
+			// If Command was called with an absolute path, we already resolved
+			// its extension and shouldn't need to do so again (provided c.Path
+			// wasn't set to another value between the calls to Command and Start).
+			lp = c.cachedLookExtensions.out
+		} else {
+			// If *Cmd was made without using Command at all, or if Command was
+			// called with a relative path, we had to wait until now to resolve
+			// it in case c.Dir was changed.
+			//
+			// Unfortunately, we cannot write the result back to c.Path because programs
+			// may assume that they can call Start concurrently with reading the path.
+			// (It is safe and non-racy to do so on Unix platforms, and users might not
+			// test with the race detector on all platforms;
+			// see https://go.dev/issue/62596.)
+			//
+			// So we will pass the fully resolved path to os.StartProcess, but leave
+			// c.Path as is: missing a bit of logging information seems less harmful
+			// than triggering a surprising data race, and if the user really cares
+			// about that bit of logging they can always use LookPath to resolve it.
+			var err error
+			lp, err = lookExtensions(c.Path, c.Dir)
+			if err != nil {
+				return err
+			}
 		}
 	}
 	if c.Cancel != nil && c.ctx == nil {